This puzzle:

JimH notes: This grid is notable for several reasons. Most remarkably, it's the first to stack five 15-letter answer words. That's an amazing accomplishment few believed possible. The grid is asymmetric. Notice the additional 15 in the top half but none in the bottom half. (I've long held that strict adherence to symmetry limits interesting grid and theme possibilities. Would a quintuple-stack be possible if symmetry were required? Do you care?) And finally, this is the first puzzle dropping HORSE MANURE into the grid.